Digital printing has begun to play an ever-increasing role in the commercial printing industry, and the demand for the capability of digital printing technologies, such as electrophotography, drop-on-demand inkjet, and continuous inkjet, to deliver high quality prints is also increasing. Various image artifacts in the spatial domain, the temporal domain, or the spatial and temporal domains adversely affect image quality. For instance, granularity is defined as the aperiodic non-uniform reflection density/color distribution in the microscopic spatial domain, and color consistency is affected by the stability of a printing press over a period of time. One artifact that plagues most of the digital printing systems is the one dimensional macro non-uniformity, which is usually denoted as streaking or banding, depending on its aperiodic or periodic characteristics. Streaking and banding can occur either parallel, perpendicular, or any other angle to the printing process direction.
A digital press is composed of many subsystems, and each subsystem can contribute to the streak/band artifact. For example, the electrophotography imaging process consists of six major steps: charge, expose, develop, transfer, fuse, and clean. The usual approach to eliminating the formation of a streak or band artifact on a digital press is to optimize each subsystem and hope the final assembled system will satisfy the product requirement. While the subsystem optimization is necessary to improve the overall system performance in image quality, it might result in a very stringent requirements or tolerances for each subsystem because of the effect of accumulating error in the final system. Furthermore, the subsystem optimization process does not address the problems arising from the interaction among subsystems.